For example, as disclosed in the Patent Document 1, there is known a hybrid vehicle which is provided with a differential mechanism having a first rotary element connected to a first electric motor, a second rotary element connected to an engine, and a third rotary element connected to an output rotary member and connected to a second electric motor through a double reduction gear, and a crankshaft locking device for inhibiting a rotary motion of a crankshaft of the engine, and which can be run in a second motor drive mode in which both of the first and second electric motors are operated as a vehicle drive power source, as well as in an ordinary first motor drive mode in which the second electric motor is operated as the vehicle drive power source. In Patent Document 2, a hybrid vehicle is disclosed that is of a type without the crankshaft locking device and with the reduction gear formed in one stage.